Clinical analysis of skip N2 metastases in stage IIIA non-small cell lung cancer

Abstract

Clinical characteristics of skip N2 metastasis of stage IIIA non-small cell lung cancer (NSCLC) are not clear. This study was to investigate the clinicopathologic features and the distribution pattern of N2 lymph nodes, thus to analyze the relationship between the survival rate and skip metastasis of NSCLC patients. Clinical data of 292 patients with stage IIIA NSCLC undergoing radical surgical resection plus mediastinal nodal dissection in the Affiliated Hospital of Nantong University were retrospectively reviewed. Clinicopathologic features, distribution of skip N2 metastasis and survival were analyzed respectively. The incidence rate of skip N2 metastasis in stage IIIA NSCLC patients was 15.8%, which was correlated to the size of the tumor (P<0.05). Moreover, the relationship between the primary tumor location and N2 positive lymph nodes were described as follows: right upper lobe cancer displayed skip-N2 nodal metastasis mostly in the 3rd and 4th station (85.7%), right middle lobe mostly in the 7th station(75.0%), right lower lobe mostly in the 3rd and 7th station(81.0%), left upper lobe mostly in the 5th and 6th station(80.0%), and left lower lobe mostly in the 7th station (65.0%). The 3-year survival rate of patients with skip N2 metastasis was 45.4%, compared to 29.5% in patients with the involvement of N1 and N2 nodes. Survival analysis showed that skip N2 metastasis was an independent risk factor of stage IIIA NSCLC in addition to tumor size, histology, type of resection, adjuvant chemotherapy and radiotherapy. In stage IIIA NSCLC, primary tumors in different locations have their own corresponding areas of N2 nodal metastasis. Skip N2 metastasis is an independent prognostic factor for the survival of NSCLC. Patients with skip N2 metastasis have a favorable outcome.